1. Field of the Invention
The present invention relates to an ultrasonic recognition system on digital network communication between a master station and detail stations by means of using a master communication device attached to the master station, detail communication devices attached to the detail stations, respectively, and identification cards set in the detail communication devices, respectively.
2. Description of the Prior Art
It is most important on digital network communication to prevent the influence of noises and invaders. However, it is difficult to keep the communication secret by the coding technique based on conventional hard-wears such as magnetic cards and IC cards. The magnetic cards are very convenient and popular, however it is easy to make copies thereof or steal passwords. Therefore damages by unlawful using of credit cards, cash cards, prepaid cards, and so on are increasing year after year. The IC cards are superior to the magnetic cards in difficulty in counterfeiting of cards, however it is not enough to keep the communication secret thoroughly. Thus, conventional hard-wears have problems on keeping a communication security.
An object of the present invention is to provide an identification card useful as credit card, cash card, key, and others.
Another object of the present invention is to provide an identification card excellent in difficulty in counterfeiting and stealing of passwords.
Another object of the present invention is to provide an ultrasonic recognition system on digital communication capable of recognizing the identification-card singularity in secret.
Another object of the present invention is to provide an ultrasonic recognition system on digital communication capable of low electric power consumption.
Another object of the present invention is to provide an ultrasonic recognition system on digital communication excellent in durability and manufacturing.
A still other object of the present invention is to provide an ultrasonic recognition system on digital communication having a small size and a simple structure.
According to one aspect of the present invention there is provided an ultrasonic recognition system on digital communication comprising a master communication device attached to a master computer, a detail communication device attached to a detail computer, and an identification card set in the detail communication device. If the identification card delivers an individual coded digital-signal via the detail communication device into a digital network, the master communication device recognizes the identification-card singularity when receiving the individual coded digital-signal through the digital network. Thus, the master communication device keeps on communicating with the detail communication device while the identification card is set in the detail communication device. In addition, for further securing such a communication system, a coded request digital-signal asking for password is delivered from the master communication device into the digital network toward the detail communication device before the communication between the master communication device and the detail communication device arises.
According to another aspect of the present invention there is provided an ultrasonic recognition system on digital communication comprising an identification card, a detail communication device, and a master communication device. The identification card consists of a first piezoelectric substrate, an individual coded interdigital transducer (IDT) having an individual coded pattern, and a first intermediary IDT. The detail communication device consists of a second piezoelectric substrate, and transmitting- and receiving sections. The transmitting section is composed of a bipolar-pulse generator, first- and second coded IDTs having first- and second coded patterns, respectively, a second intermediary IDT, first- and second side IDTs, a central IDT between the first- and second side IDTs, a synchronizing device connected between the second intermediary IDT and the first side IDT, an envelope detecting device connected with the central IDT, and a monopolar-pulse generator. The first- and second side IDTs and the central IDT form an electrode group. The master communication device has the same construction as the detail communication device, and consists of a third piezoelectric substrate and transmitting- and receiving sections. The receiving section is composed of a third intermediary IDT, third- and fourth coded IDTs having third- and fourth coded patterns, respectively.
If the identification card is set in the detail communication device, a pulse is generated at the bipolar-pulse generator, and is applied to individual coded IDT. In this time, an individual SAW corresponding to the individual coded pattern is excited on the first piezoelectric substrate, and is detected at the first intermediary IDT as an individual coded burst-signal. When the individual coded burst-signal arrives at the first- and second side IDTs, respectively, first- and second SAWs are excited on the second piezoelectric substrate, respectively. The first- and second SAWs arrive at the central IDT simultaneously. And then, an individual coded digital-signal is obtained at the monopolar-pulse generator via the envelope detecting device, and is delivered into a digital network. On the other hand, if the individual coded digital-signal arrives at the master communication device, it is received at the third intermediary IDT. In this time, a third SAW composed of an individual coded row of burst-wave groups is excited on the third piezoelectric substrate. When the burst-wave group correlates to the third- and fourth coded patterns, respectively, first- and second decoded pulses are detected at the third- and fourth coded IDTs, respectively. As a result, an output digital-signal equivalent to the individual coded pattern, is detected at the detecting device. Therefore, the identification-card singularity is recognized from the output digital-signal.
In addition, for further securing such a communication system, a coded request digital-signal asking for password is delivered from the transmitting section of the master communication device into the digital network toward the detail communication device just after recognition of the identification-card singularity. The coded request digital-signal asking for password is received at the receiving section of the detail communication device through the digital network. And then, a coded password digital-signal is delivered from the transmitting section of the detail communication device into the digital network. When the coded password digital-signal is received at the receiving section of the master communication device through the digital network, it is converted into an output digital-signal equivalent to the password digital-signal. Thus, the communication between the master communication device and the detail communication device starts.
According to another aspect of the present invention there are provided first-, second-, third-, and fourth coded IDTs consisting of at least three interdigital electrode pairs, respectively.
According to another aspect of the present invention there are provided third- and fourth coded IDTs having third- and fourth coded patterns in reverse to the first- and second coded patterns, respectively.
According to another aspect of the present invention there is provided an individual coded IDT constructed of multiple times four coded IDTs classified into at most two types that correspond to the first- and second coded IDTs, respectively.
According to another aspect of the present invention there is provided a bipolar-pulse generator in place of the monopolar-pulse generator.
According to other aspect of the present invention there is provided an individual coded IDT comprising at least two parts that are electrically separated and in uneven parallel with each other. The parts excite individual SAWs, respectively, on the first piezoelectric substrate when receiving the pulse from the bipolar-pulse generator simultaneously. The first intermediary IDT receives the individual SAWs one by one, and detects a mixed individual coded burst-signal corresponding to the individual coded pattern.
According to a further aspect of the present invention there are provided an individual coded IDT comprising first- and second parts that are electrically separated and vertical from each other, and an identification card further comprising a fourth intermediary IDT. The first- and second parts excite first- and second individual SAWs, respectively, on the first piezoelectric substrate when receiving the pulse from the bipolar-pulse generator simultaneously. The fourth intermediary IDT detects a first individual coded burst-signal corresponding to the first individual SAW. The first intermediary IDT detects a second individual coded burst-signal corresponding to the second individual SAW just after the fourth intermediary IDT detects the first individual coded burst-signal. The first- and second individual coded burst-signals form a mixed individual coded burst-signal corresponding to the individual coded pattern.